Containers for receiving goods are widely used. Usually, the containers which may be vials are opaque such that the goods received in the container are not visible. To identify the good, there are inscriptions and/or pictures which are useful for selling and for the customer in order to select the goods which meet his desire.
To facilitate identification and tracking, such a container may have a bar-code which may be an EAN-code. A more sophisticated and advanced technique uses a transponder comprising a RFID chip. Such a transponder has to use an antenna which is formed on a flat disc with electric conductors being printed thereon. To allow an identification, electromagnetic waves are used. Thus, a minimum extension of the antenna is required and the antenna efficiency relies on having a specific form, such as the form of a flat spiral.
Although the use of RFID tags in a cover of such a container has already been proposed, there are several problems. With small containers, the area which may be used for receiving the tag is limited. This leads to a small antenna with a limited range of operation. On the other hand, such a transponder is subject to errors by external influences. A piece of metal arranged close to the container may influence the electromagnetic fields and the frequency selected for the transponder such that the transponder does not react properly.
To improve the independence from external influences, it has been proposed in DE GM 201 05 605 to receive the RFID chips in a mass made from polyurethane. However, during long term, the transponder of such a construction is not stable, and thus it is not reliable.
Also, it has been proposed in to incorporate a transponder directly into the plastic material of a container cover and to use a ring-shaped antenna which also acts as a capacitor and is operational as long as the container is closed. However, this structure is rather complicated to produce and requires a specific arrangement of the RFID chip. The thickness of the cover must be increased in order to safely receive the chip, and it is difficult to have the antenna in a flat arrangement, if it is not produced as a sheet covering the cover or lid from the outside. In the latter case, however, the container is not tamper-proof.